The article discusses the debates surrounding the status of Pluto as a planet and gives background information into how a particular celestial body is classified as a planet. Such news related to space has become important for mains. Last year, UPSC had asked a question on Juno mission. Also, such small pieces of information is sometimes asked in mains like the 2013 question where they asked how storms are named.

Key demand of the question

The question expects us to explain first the criteria followed in classifying celestial objects as planets. Thereafter, we need to provide a brief context into the debates surrounding the status of Pluto as a planet, and explain why scientists are reconsidering the decision to downgrade Pluto as a planet.

Directive word

Discuss – This is an all-encompassing directive – you have to debate on paper by going through the details of the issues concerned by examining each one of them. You have to give reasons for both for and against arguments.

Structure of the answer

Introduction – Mention that in 2006, the International Astronomical Union (IAU) voted to remove Pluto’s planetary status and now scientists are debating once again over the taxonomy of planets.

Body

Explain how celestial objects are classified as planets – The meeting of IAU in 2006, where Pluto’s status as a planet was being decided, defined three conditions for a celestial object to be called a planet: one, it must orbit the Sun; two, it should be massive enough to acquire an approximately spherical shape; three, it has to ‘clear its orbit’, that is, be the object that exerts the maximum gravitational pull within its orbit. Also explain what a dwarf planet is.

Explain the reasons why Pluto was no longer considered a planet – insufficient gravity of Pluto in comparison to Neptune – the reason why it got classified as a dwarf planet

Explain why some scientists are reopening the case of Pluto’s status – that the only work in history that used this rule to classify planets was an article by William Herschel in 1802. They also argue that this work was based on reasoning and observations that have since been disproved.

Conclusion – Explain the issues that might arise by challenging the classification done by IAU.